1. Field of Invention
The present invention relates to ships or other watercrafts, and more particularly to a trimaran with a planing surface and a rigid sidewall.
2. Description of Related Arts
In the past thousands of years, for conquering rivers and lakes, people living on land have been tirelessly researching watercrafts. In order to reduce the resistance of sailing, planing boats, hovercraft, and other kinds of ships have been designed and improved.
The planing boat is a high-speed ship whose weight is mainly supported by hydrodynamic pressure to the body from water when sailing. The planing boat is shorter and wider than the conventional displacement ship, and the bottom is relatively flat. A joint of bottom and side plate of the conventional ship is usually a sharp corner which forms a sharp bilge, wherein this kind of ship is also called a sharp bilge boat. Because the planing boat relies on hydrodynamic pressure acting on a part of the hull for lifting most of the hull out of the water when sailing with a high-speed, a normal draft thereof is required not to be too deep when the boat is in a non-planing state. Otherwise, it will be difficult to start planing. Therefore, the planing boat is not suitable for being enlarged. In addition, the sea state has a great effect on the planing boat when sailing. Because the direct impact of wave on the hull is large, when the sea state is high, the boat will jump like a dolphin, so that the seaworthiness is seriously lowered.
There are two main types of hovercrafts: cushion hovercraft and sidewall hovercraft. During sailing, the whole hull is lifted out of the water by a high-pressure air cushion. Because of no water resistance, not only sailing speed is high, but also the adaptability is sufficient. However, the hovercraft needs more lifting power, which may be up to 50% of a total power, when sailing. As a result, operation economy of the hovercraft is greatly decreased.